Social Security & 401(k) Calculator — Plan Your US Retirement
Two decisions dominate US retirement planning: when to claim Social Security, and how to balance your 401(k) and Roth IRA. Get these right and you can add tens of thousands of dollars in lifetime income. Get them wrong and you may pay more in taxes than necessary — or outlive your savings. This guide covers both with real numbers.
Social Security Claiming Strategy: Age 62, 67, or 70?
Social Security is the only guaranteed inflation-indexed lifetime income most Americans will have. Your Full Retirement Age (FRA) is 67 if you were born in 1960 or later. You can claim as early as 62 or as late as 70:
| Claiming Age | Adjustment | Monthly Benefit (base $2,000) | Annual Benefit |
|---|---|---|---|
| 62 | −30% | $1,400 | $16,800 |
| 64 | −20% | $1,600 | $19,200 |
| 67 (FRA) | 0% | $2,000 | $24,000 |
| 68 | +8% | $2,160 | $25,920 |
| 70 | +24% | $2,480 | $29,760 |
Claim early (62–64) if…
- You have health concerns or a family history of shorter life expectancy
- You need income to retire before 67 without draining savings
- You have a high-earning spouse who is delaying their own SS
Delay to 70 if…
- You are in good health and expect to live past 80–82
- You have 401k/IRA savings to bridge the gap to age 70
- You want maximum longevity insurance against a long retirement
The break-even age between claiming at 62 vs. 70 is typically around 80–82. If you live past that, delaying to 70 produces higher lifetime income. Social Security is also taxable — up to 85% of your benefit is included in taxable income depending on your provisional income.
401(k) vs. Roth IRA: How to Model Both
The core trade-off: a Traditional 401(k) saves you taxes now (contributions are pre-tax), while a Roth IRA saves you taxes later (withdrawals are tax-free). Which is better depends on whether your tax rate is higher today or in retirement.
Traditional 401(k)
- 2025 contribution limit: $23,500 ($31,000 if age 50–59 or 64+; $34,750 if age 60–63)
- Employer match is common — this is free money, always contribute at least enough to get the full match
- Withdrawals in retirement are taxed as ordinary income
- Required Minimum Distributions (RMDs) start at age 73 (age 75 for those born in 1960 or later)
Roth IRA
- 2025 contribution limit: $7,000 ($8,000 if age 50+). Income limits apply for direct contributions.
- Contributions are after-tax — no tax deduction today
- All qualified withdrawals are completely tax-free, including growth
- No RMDs during the owner's lifetime — Roth is the most flexible retirement account
A common strategy is to contribute to both — maxing the 401(k) to get the full employer match, then contributing to a Roth IRA for tax diversification. In retirement, drawing from traditional accounts first (and meeting RMD requirements) while letting Roth grow tax-free gives you maximum flexibility.
Required Minimum Distributions (RMDs): What to Know
The IRS requires you to withdraw a minimum amount from traditional IRAs and 401(k)s each year starting at age 73 (or 75 if born in 1960 or later, per SECURE 2.0). The amount is calculated by dividing your account balance by your life expectancy factor from the IRS Uniform Lifetime Table.
Sample RMD Calculation at Age 73
RMDs are taxed as ordinary income and can push you into a higher bracket or increase the taxable portion of your Social Security. The Solutech planner calculates your RMD each year and shows any surplus mandatory withdrawal separately in the income sources chart.
Calculate Your US Retirement Projection — Free
Enter your Social Security benefit, claiming age, 401(k) balance, employer match, and Roth IRA. The planner models taxes on traditional withdrawals, RMDs, and runs 1,000 Monte Carlo scenarios to show your probability of success.
Run Your US Retirement ProjectionFree · No account needed · Results in seconds
Frequently Asked Questions
How much Social Security will I receive?
Your benefit is based on your highest 35 years of indexed earnings. The SSA calculates your Primary Insurance Amount (PIA), which is the benefit you receive at Full Retirement Age (67 for those born 1960+). You can find your estimate at ssa.gov. The average retirement benefit in 2024 is about $1,907/month.
What is the Social Security break-even age?
The break-even age between claiming at 62 vs. 70 is typically around 80–83, depending on your specific benefit amounts. If you expect to live past that age, delaying to 70 produces more total lifetime income. If you have health concerns, claiming earlier may make more sense.
How are Social Security benefits taxed?
Up to 85% of your Social Security benefit may be taxable depending on your "provisional income" — which is your adjusted gross income + non-taxable interest + 50% of your SS benefit. If provisional income exceeds $34,000 (single) or $44,000 (married), up to 85% of SS is taxable.
What happens if I contribute to a 401(k) and a Roth IRA?
You can contribute to both in the same year, subject to the limits for each account ($23,500 for 401k, $7,000 for IRA in 2025). This gives you tax diversification — some savings taxed now (Roth) and some later (401k) — which can reduce your lifetime tax bill.
What is the 2025 401(k) contribution limit?
In 2025, you can contribute up to $23,500 to a 401(k). If you are age 50–59 or 64+, the catch-up limit raises this to $31,000. A new SECURE 2.0 provision gives ages 60–63 a super catch-up limit of $34,750.